 |
 |
Monday March 2, 1998 How Lithium Helps Manic Depression NEW YORK (Reuters) -- The drug lithium has been used to treat manic depression for 50 years, but it has never been clear how it actually works. Now, researchers have discovered that lithium protects brain cells from damage due to excessive amounts of glutamate, an important chemical messenger in the brain. In a report published in the Proceedings of the National Academy of Sciences, researchers led by Dr. De-Maw Chuang of the National Institutes of Health in Bethesda, Maryland, describe studies they conducted with neurons (nerve cells) from rat brains. The investigators discovered that treatment with lithium "dramatically protects" rat neurons against the lethal effects of too much glutamate. The investigators found that lithium had an effect on glutamate receptors, specific sites at which the glutamate attaches itself to the neuron. These glutamate receptors regulate the amount of calcium that enters the neurons. By controlling the glutamate receptors, lithium affects the extent to which calcium can enter the cells. The authors note that six to seven days of lithium treatment was necessary for "complete protection" of the cells. Treatment for only 24 hours was ineffective." "Our results suggest that modulation of glutamate receptor(s)... represents at least part of the molecular mechanisms by which lithium... exerts its (effect in)... manic depressive illness," the investigators write. "These (findings) also suggest that (abnormal glutamate neurotransmission may underlie) bipolar illness." A press release from the publishers of the journal points out, "Since glutamate has been implicated in brain-cell death in Huntington's, Alzheimer's, and PARKINSON'S diseases as well as brain stroke, these findings also raise the possibility that lithium may prove useful in the treatment of these neurodegenerative disorders." SOURCE: Proceedings of the National Academy of Sciences USA (1998;95:2642-2647) Copyright © 1998 Reuters Limited.